This invention relates to a check valve assembly which includes certain features for insuring proper orientation of one or more check valve elements in a flow line, and for permitting proper orientation of a spider spacer element located between the check valve(s) and an inlet passageway of the check valve assembly.
In drinking water systems, many municipalities require some mechanism to insure against backflow from end user installations into the potable water supply. When water pressure in the potable water system is unusually low, or if high pressure occurs at end user locations, reverse flow from the end user area into the potable water system is possible. This reverse flow can contaminate the water supply. In areas where pesticides and herbicides are commonly used, as well as in other areas in which environmentally dangerous chemicals are found, the existence of back flow conditions may pose special contamination risks. Back flow prevention devices are usually placed in a water line at or near the point where an individual service connection taps into the common supply line. In this manner, contaminates present at the point of use are kept separated from the potable supply source of water. This is normally accomplished by placing a one-way check valve in the water line to stop reverse flow and provide anti-syphoning control when water pressure in the potable water system gets too low.
Applicant previously developed a right angle check valve assembly wherein plural check valves are provided. Applicant's prior art system incorporates a dual check valve system in a right-angled pipe housing. Two one-way check valve units are inserted into a passageway of the right-angled pipe through a screw closure mechanism which is aligned with a flow axis of the passageway. The closure mechanism includes an integral spider spacer cage which extends outwardly from threads which are used to hold the closure mechanism to the pipe housing. After the one-way valve(s) are inserted into the passageway, the closure mechanism is threaded into the angled pipe housing to seal the passageway. The spider spacer cage is located at a juncture of the inlet passageway and the vertical outlet passageway of the assembly. Water (or another fluid) flows into the assembly through the inlet passageway, passes through the spider spacer cage and the check valves, and then exits through the outlet passageway of the assembly.
It is an object of the instant invention to improve upon Applicant's prior art assembly by providing flow enhancing modifications and safety features to insure correct orientation of the spider spacer cage and correct orientation of the one-way valve units in the system.
In the prior art systems the valve housing and closure are often made of bronze or other metal castings. The spider spacer cage is cast integral with the closure. As the closure is screwed into the housing, ports inside of the spider spacer cage did not always align themselves with the inlet passageway, thus causing a restricted flow through the system.
In order to improve the flow through the system, the instant invention contemplates making the spider spacer cage out of a plastic material and attaching it to the cast closure member by a snap-in fit which allows for relative rotation between the spider spacer cage and the closure member. In particular, the closure has an internal groove to which the spider spacer cage is attached by way of wedges on upper extendinq legs of the spider spacer cage. These wedges can ride in the grooves to allow for relative rotation of the spider spacer cage and the closure member, while at the same time, rotation of the rotatable closure member causes axial movement of the spider spacer cage. As the closure is rotated to close and seal the entry to the check valve assembly, the spider cage is forced downward to press against the one-way valve units in a manner to be discussed below. When (or as) the closure is completely tightened, a tool can be inserted into the inlet passageway and through a side opening in the spider spacer cage so as to be able to rotate the spider spacer cage to a position where the opening is aligned with the inlet passage. In this manner, the flow restrictive nature of the spider spacer cage is minimized.
It is another object of the invention to provide a safety feature to insure that the one-way valve(s) are inserted in the proper direction, which direction only permits flow from the inlet passageway through the outlet passageway and prohibits reverse flow or syphoning from the outlet passageway into the inlet passageway whereby contamination of the source of water could occur.
To this end, the check valve assembly is provided with an abutment at the bottom-most end of the outlet passageway. This abutment defines the lowest level of insertion for the one-way valve units. An indexing connection is provided between the one-way valve units and the abutment and the spider spacer cage which allows the valve units to telescope over each other and the abutment and the spider spacer cage to telescope over the inlet end of one of the one-way valve units. The index connection prevents telescoping when one of the one-way valve units is oriented in an improper direction, preventing complete closure of the assembly and indicating the improper orientation.
In the double valve unit failsafe system, two one-way valve units are placed in the outlet passage, one atop the other. Here the inlet end of the lower valve unit is indexed to the outlet end of the upper valve unit so that the lower end of the upper valve can telescope over the inlet end of the lower valve unit. Similarly, a lower end of the lower valve unit is indexed with an abutment at the outlet end of the outlet passageway to allow for a telescoping of the lower valve unit into the abutment. The spider spacer cage is indexed for telescoping over the inlet end of the upper valve unit.
If either, or both, of the valve units are inserted in the reverse direction, all of the aforementioned telescoping relationships cannot occur since the indexing cannot take place when a bottom of the valve unit abuts either a bottom of the spider spacer cage or the inlet of the other valve unit, or if the inlet of a valve unit abuts the abutment at the bottom of the outlet passage.
The distance between the entry closure means and the abutment is such that the telescopic overlapping of the spider spacer cage, the one-way valve(s) and the abutment must each occur, or else the stacking of the spider spacer cage and the valve unit(s) will cause their length in the outlet passage to exceed that distance which would permit the closure means from reaching a closed position. When the valve unit(s) are properly aligned to permit flow from the inlet passageway to the outlet passageway, their length is such that the spider spacer cage can telescope over a valve unit as the closure is rotated to close off and seal the entry while it axially moves the spider spacer cage downwardly.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.